Copyright Goodheart-Willcox Co., Inc. 146 Gas Tungsten Arc Welding Handbook Overlap. Weld metal that has fl owed over the edge of the joint and improperly fused with the base metal. How to correct: • Clean edge of weld joint. • Remove oxides from previous welds. • Reduce size of bead. • Increase travel speed. • Maintain proper torch angles. Undercut. Lack of fi ller metal at the toe of the weld metal. How to correct: • Maintain proper torch angles. • Decrease travel speed. • Increase dwell time at edge of joint on weave beads. • Decrease arc length. • Decrease amperage. Underfi ll. A concave weld occurs when insuffi cient metal is added to fi ll the joint above the groove edges. How to correct: • Add additional fi ller metal on the fi ll passes. • Use stringer beads on crown pass. Excessive face reinforcement. A weld that is peaked in the center. How to correct: • Use less fi ller metal on the crown bead.